2. • Biogas is a clean and efficient fuel. Anecdotal evidence indicates that biogas was used for heating bath water
in Aasyria during the l0th century BC and in Persia during the 16th century. Jan Baptita van Helmont first
determined in 17th century that flammable gases could evolve from decaying organic matter. The pioneer of
anaerobic digestion in India is S.V. Desai, for his first experiments on biogas production in 1939. This led to
the development of the first Indian biogas plant in 1951, the Gramalaxi plant of the Khadi and Village
Industries Commission (KVIC), better known as the KVIC digester.
• Biogas is a mixture of gases ,composed of – a. Methane [CH4]
b. CO2
c. H2S
d. N2, H2,CO and other….
• The percentage of methane to carbon dioxide varies depending on the feedstock and the completeness of the
process (world energy council, 1994). The biogas produced contains usually 50-65% methane, 35-50% carbon
dioxide (world energy council, 1994).
INTRODUCTION:
3. Continuing……….
• There are many other common names for biogas– gobar gas, sewage gas, klar gas and sludge gas.
• It is a gaseous fuel and serves as a good source of energy for various purposes.
1. It can be used for cooking purposes [on combustion]
2. Gobar gas can generate electricity.
3. It can be purified to obtain good grade methane.
etc.
• It is estimated that under ideal conditions, 10kg of biomass can produce 3𝑚3of biogas. This biogas can
provide 3 hour cooking, 3 hour lighting or 24 hour refrigeration . The calorific value of biogas [with higher
content of methane] is around 8,500 cal/𝑚3
4. • Biogas production significantly contributes to the world's energy source. China has the largest number of
biogas or gobar gas systems, with an estimated 7 million units.
• Govt. of China encourages and offers subsidies for construction of biogas units . As a result , the cost of a
biogas plant is cheaper than a bicycle in China.
• Government in many developing countries also encourage installation of biogas plants. In India,
Government provides 25% subsidy , besides encouraging banks to offer loans for construction of biogas
plants . They are becoming popular in rural areas .
BIOGAS PRODUCTION IN DIFFERENT COUNTRIES
5. • The usual substrates for biogas production are the waste product of animal husbandry, industries,
agriculture and municipalities. In India and other developing countries, cattle dung [gobar] is most
commonly used. The major raw material for biogas production in China is pig dung.
• The conc. Of organic dry matter or total solids [TS] is useful for grading the industrial, agricultural and
municipal wastes.
• Thus, low grade [≤ 1% TS] , medium grade [1-5% TS] , high grade [5-20% TS] and solid wastes [20-40%
TS] are available .Solid or high grade wastes are preferred as best substrates for biogas production.
• In general, most of the substrates used in biogas plants contain adequate quantities of almost all the
essential nutrients required for microbial growth . If necessary , nitrogen, phosphorous & other trace
elements are added .
• Huge biomass of water hyacinth & Azolla – for biogas production [ CH4 generation].
SUBSTRATES FOR BIOGAS
C/N ≤ 40:1, for optimal biogas
production
6. MICROBIAL PRODUCTION OF CH4 [BIOGAS]
• CH4 is the most abundant constituent of biogas. It can also be directly used for various domestic & industrial
purposes. The microbial generation of CH4 , appropriately referred to as methanogenesis from biomass
occurs in 4 phases.
[Microbial production of methane]
7. Continuing……
..
1. Hydrolytic phase-
2. Acidifying phase-
3. Acetogenic phase-
4. Methanogenic phase-
Cellulose , Starch, Proteins, Lipids etc.
Low mol. wt. soluble
products & some organic
acids
Low mol. wt. soluble products &
some organic acids
H2, CO2, alcohol & some
organic acids
H2, CO2 & alcohol
Acetate
Acetate along with H2, CO2
CH3COOH CH4+CO2
4H2+CO2 CH4+2H2O
formate, methanol , glucose
Methane
8. PROCESS OF BIOGAS PRODUCTION FROM BIOGAS PLANT
• Biogas production from biomass is an
anaerobic process. The anaerobic process is
usually carried by using air tight cylindrical
tanks which are referred to as anaerobic
digesters.
• A digester may be made up of concrete
bricks & cement or steel, usually built
underground. The digester has an inlet
attached to a mixing tank for feeding cow
dung and other wastes . The Methanogenic
Bacteria are also added with the biomass.
• The digester is attached with a movable
storage tank with a gas outlet. The used
slurry comes out from the digester through
an outlet. This can be used as manure.
• The anaerobic digester described right side
, is a low technology gobar gas plant,
commonly used for domestic purposes in
rural areas in India. The process of digestion
usually takes about 2-3 weeks when cow
dung is used as the substrate.
9. TYPES OF BIOGAS PLANT
There are two types of biogas plants in usage for the production of biogas. These
are:
1. The fixed- dome type of biogas plant
2. The floating gas holder type of biogas plant
1. Fixed-dome type of plant was first discovered by China.
Temperature const. type biogas plant as it is inside the soil.
Dome vol. is constant ,so called constant volume dome type
biogas plant .
Advantage- Low cost , It uses cement only.
- It has no corrosion problem.
-Space above the plant can be used for other
purposes.
Disadvantage- Gas production per 𝑚3
of the digester vol. is less. It
requires skilled machinery of construction.
- Variable gas pressure.2. Floating gas –holder type biogas plant- Its popular model
was developed in India.[KVIC]. A steel tank is there for gas
collection, i.e. floating gas holder . Pressure const. type
plant.
2 types bacteria[ acid forming and methane forming
bacteria] are used for digestion process of biomass.
Advantage- Gas production rate is higher , no gas leakage
problem.
Disadvantage- High initiation and maintenance cost.
10. FACTORS AFFECTING BIOGAS [METHANE]
1. Temperature & pH : The ideal temperature is 30-40 degree Celsius , while pH is 6-8 , for best yield.
2. Slurry composition : The ratio between solid & H2O composition in the slurry should be around 1:1 .
A carbon nitrogen ratio of 30:1 or 40:1 in the slurry results in optimal methane
production. Good mixing & solubilization of the organic wastes is required.
3. Anaerobic conditions: Digester should be completely airtight, so as to create suitable anaerobic
conditions.
4. Presence of inhibitors: Ammonium sulfate & antibiotics inhibits methane production. Some
agricultural wastes, pig and chicken manure generating ammonia and wastes
from paper rich in sulfate inhibit biogas production.
11. • By using a simple technology , agricultural, industrial and municipal wastes can be converted into a
biofuel. The left over residue after biogas formation can be used as organic fertilizers. Thus, the waste
material that would cause environmental pollution are fruitfully utilized for biogas and fertilizer production
.It's a clean & renewable energy source.
• It reduces soil & water pollution.
• Prevents health problems & biodiversity loss.
• It’s a simple and low-cost technology that encourages a circular economy.
• Healthy cooking alternative for developing areas.
ADVANTAGES OF BIOGAS PRODUCTION
12. SOME EXAMPLES:
A biogas bus in Linköping,
Sweden
"Biogaståget Amanda" ("Amanda the Biogas
Train") train near Linköping station, Sweden
Biogas production in rural
Germany
NIT, Silchar, India
Biogas plant
Kerala Man Makes Portable Plant That Provides 2 Hrs of Biogas & 4 Kg of Manure Daily!
13. Continuing………..
Biogas Research Centre In India-
• Institute Of Minerals & Materials Technology (IMMT) Bhubaneswar.
• Central Electro Chemical Research Institute, (CECRI), Karaikudi.
• Indian Institute Of Technology (IIT), Bombay.
• Anna University, Chennai.
• Indian Institute Of Chemical Technology (IICT), Hyderabad.
• Indian Institute Of Science (IISC), Bangalore.
• Indian Institute Of Technology (IIT), Guwahati.
• The Energy Resources Institute (TERI), New Delhi.
• NIT, Silchar.
• National institute for interdisciplinary science & technology (NIIST), Thiruvananathapuram.
• Biogas Development And Training Centre, Centre For Rural Development And Technology, 289, Block III, Indian Institute Of
Technology, Delhi, HauzKhas New Delhi – 110016.
• Gujarat Energy Research And Management Institute (GERMI), Gujarat.
14. • Microbial production of CH4 is more expensive than its isolation from the natural gas.
• CH4 production by gasification of coal is more economical than its production from biomass.
• Being a gaseous fuel, it is quite difficult as well as expensive to store , transport and distribute methane.
• Methane is unsuitable for use as a fuel in automobiles. This is because it is very difficult to convert the
gaseous CH4 into liquid state.
• Bio gas contains some gases as impurities, which are corrosive to the metal parts of internal combustion
engines.
• Biogas can cause obnoxious smells.
• It can produce very limited quantity of electricity on a global scale.
• Transportation is biggest issue. It is very difficult to transport the bio gas. So if you are looking for
commercial purpose than it is very difficult and costly process to store at one place and transport.
etc.
LIMITATIONS FOR LARGE SCALE PRODUCTION OF BIOGAS
[METHANE]
15. • Anaerobic digestion- It is a natural process in which in which bacteria convert organic materials in to
biogas, in the absence of O2. The process is used for industrial or domestic purposes to manage waste or to
produce fuels. Much of the fermentation process used industrially to produce food & drink products , as well
as home fermentation , uses anaerobic digestion .
• It occurs in marshes and wetlands , and the digestive tract of ruminants.
• Elements of anaerobic digestion system- Manure collection and handling, pretreatment, anaerobic digestion,
by-product recovery and effluent use , biogas recovery , handling and use of biogas.
• Examples of some anaerobic fermentations- ethanol fermentation , lactic acid fermentation ,
methanogenesis etc.
MICROBIOLOGY OF ANAEROBIC FERMENTATION:
16. • The Methanogens , a group of chemolithotrophic archaebacteria are able to convert CO2 to CH4, using
electrons from molecular hydrogen to reduce CO2 to CH4 in a specialized anaerobic digestion pathway.
• Examples of some methanogens are- Methanobacterium,Methanospirillium, Methanothrix,
Methanococcus, Methanopyrus etc.
• Such bacteria appear to have been among the earliest live on earth because they can grow autotrophically
on H2 and CO2 under anaerobic conditions.
• Conversion of CO2 to CH4 , using H2 as an electron donor is an exergonic reaction with a ΔG0of -31
kcal/mole.
• Several cofactors unique to this system have been identified . For every molecule CO2 converted to CH4 ,
one molecule of ATP is generated, along with NADPH. This NADPH is used for the incorporation of CO2
into macromolecules of the cell. Approx. 90-95% of CO2 used by methanogens is converted to CH4.
METHANOGENESIS
17. CONTINUING…………
The biochemistry of methanogenesis involves the
following coenzymes and cofactors: F420,
coenzyme B, coenzyme M, methanofuran,
and methanopterin.
![• Biogas is a clean and efficient fuel. Anecdotal evidence indicates that biogas was used for heating bath water
in Aasyria during the l0th century BC and in Persia during the 16th century. Jan Baptita van Helmont first
determined in 17th century that flammable gases could evolve from decaying organic matter. The pioneer of
anaerobic digestion in India is S.V. Desai, for his first experiments on biogas production in 1939. This led to
the development of the first Indian biogas plant in 1951, the Gramalaxi plant of the Khadi and Village
Industries Commission (KVIC), better known as the KVIC digester.
• Biogas is a mixture of gases ,composed of – a. Methane [CH4]
b. CO2
c. H2S
d. N2, H2,CO and other….
• The percentage of methane to carbon dioxide varies depending on the feedstock and the completeness of the
process (world energy council, 1994). The biogas produced contains usually 50-65% methane, 35-50% carbon
dioxide (world energy council, 1994).
INTRODUCTION:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)